The present invention relates generally to injection needles and relates more particularly to an injection needle incorporating visualization.
Nearly half of all Americans suffer from heartburn at least once a month. Heartburn occurs when stomach fluids and acids escape from the stomach and enter into the esophagus, irritating the esophagus. Normally, a muscular ring called the lower esophageal sphincter (LES) acts as a valve between the esophagus and the stomach to allow food to pass from the esophagus into the stomach while keeping stomach fluids and acids from escaping from the stomach into the esophagus. In those instances in which the LES fails to keep stomach fluids and acids in the stomach, heartburn occurs.
For some people who suffer from heartburn, the heartburn is severe enough or frequent enough to disrupt their daily activities and/or their sleep. Such a condition is called gastroesophageal reflux disease (GERD). In some people who have GERD, the LES relaxes more than it should and/or at the wrong times.
In addition to causing frequent and/or severe heartburn, GERD can cause other health problems. For example, the fluids and acids that reflux into the esophagus can lead to inflammation of the esophagus (esophagitis) or ulcers. In severe cases, this damage can scar the esophageal lining and narrow it, causing a stricture which may make it hard or painful for the patient to swallow. In certain cases, this may lead to a condition called Barrett's esophagus, where the lining of the esophagus changes and may over time lead to cancer of the esophagus.
Many people can get relief from GERD symptoms by changing their diet and/or using appropriate medications. Some of the medications available for managing GERD symptoms include common antacids as well as drugs that slow down the production of stomach acids, such as proton pump inhibitors and H2 receptor antagonists.
It should be noted, however, that medications of the type described above merely address symptoms of GERD and do not address the condition's mechanical etiology. Thus, GERD symptoms often recur after drug withdrawal. In addition, while medications may effectively treat the acid-induced symptoms of GERD, they do not treat alkaline reflux, which may result in esophageal mucosal injury.
In any event, because GERD is a chronic condition, it may be necessary for a patient to take medications for the rest of his life in order to continue to obtain relief from GERD symptoms. However, for many patients, the expense and the psychological burden of a lifetime of medication dependence, as well as the uncertainty of long-term effects of some newer medications and the potential for persistent mucosal changes despite symptomatic control, make surgical treatment an alluring alternative to a medicinal approach. As can readily be appreciated, however, surgical intervention, often in the form of anti-reflux surgery, is a major undertaking and includes its own set of risks.
Fortunately, a minimally invasive technique has been devised for treating GERD. This technique, which is more fully disclosed in U.S. Pat. Nos. 6,238,335, 6,251,063, 6,351,064 and 6,695,764, all of which are incorporated herein by reference, typically involves first inserting an endoscope down through the patient's mouth and into the esophagus in proximity to the LES. Then, the distal end of a device commonly referred to as “an injection needle” is inserted through a working channel of the endoscope, and a needle at the distal end of the injection needle is inserted into the muscle of the LES. Then, a special solution is dispensed through the injection needle and into the muscle of the LES. The solution includes a biocompatible polymer that forms a soft, spongy, permanent implant in the sphincter muscle that helps the LES to keep stomach fluids and acids from backing up into the esophagus.
Typically, an injection needle of the type referred to above comprises a hollow needle, a flexible inner catheter, a flexible outer catheter, an inner hub and an outer hub. The proximal end of the hollow needle is typically fixedly mounted within the distal end of the flexible inner catheter. The inner hub is typically fixedly mounted on the proximal end of the inner catheter and is adapted to convey fluids to the inner catheter from a needleless syringe or the like. The inner catheter and the hollow needle are typically slidably mounted within the outer catheter so that one may extend the hollow needle out of the distal end of the outer catheter when one wishes to make an injection and retract the hollow needle into the outer catheter when not making an injection. The outer hub is typically fixedly mounted on the proximal end of the outer catheter and is adapted to engage the inner hub so as to limit the distal movement of the needle and the inner catheter relative to the outer catheter. Examples of injection needles are disclosed in the following patents, all of which are incorporated herein by reference: U.S. Pat. No. 6,770,053; U.S. Pat. No. 6,585,694; U.S. Pat. No. 6,423,034; U.S. Pat. No. 6,401,718; U.S. Pat. No. 6,336,915; U.S. Pat. No. 5,785,689; U.S. Pat. No. 4,946,442; and U.S. Pat. No. 4,668,226.
Typically, certain measures are taken to promote proper placement of the distal tip of the injection needle in the targeted tissue. For example, where the injection needle is delivered to the patient via the working channel of an endoscope, the endoscope is typically additionally equipped with a light and a camera so that one can view, in real-time, the environs of the distal end of the endoscope; in this manner, the targeted penetration site may be identified. In addition, to promote a proper penetration depth of the needle into the targeted tissue, the needle is typically dimensioned to extend from the distal end of the inner catheter by a length corresponding to the desired penetration depth. However, as can be appreciated, tissue thicknesses vary from patient to patient. Moreover, because tissue is easily compressed and because tissue may be penetrated by the inner catheter as well as by the needle, the depth of needle penetration cannot always be controlled by dimensioning the needle in the above manner. For this reason, fluoroscopy is often employed to provide live X-ray images of the injected solution that indicate if the needle has been inserted too far through the tissue.
In addition to being used in the above fashion to treat GERD, injection needles are also useful in injecting other treatment materials, such as drugs, treatments for bleeding, etc.